It is well established that bacteria play a dominant role in peridontal disease. Several gram-negative bacteria have been found which possess high periodontopathic potential. These bacteria include among others, members of the genus Bacteroides, Capnocytophaga, Eikenella, and Actinobacillus. Little information is available on the role of these bacteria, especially that of cell components (outer membrane and associated heteropolymers) in bacterial-host interactions; interactions and responses which may ultimately lead to peridontal disease. Most studies have investigated the role of LPS in cell mediated events, with very few studies involving bacterial cell surface components. The objective of this proposal is to examine the morphology, chemical nature, and biological activity of outer membrane and associated heteropolymers from Capnocytophaga, and Bacteroides species. Cells will be grown under rigorously controlled conditions, and associated and excreted heteropolymeric compounds will be isolated by alcohol and detergent action; outer membrane by shear and Henning Ghost production, and LPS, peptidoglycan and periplasmic-free and membrane-associated hydrolytic enzymes by biochemical and biophysical techniques. Purification will rely heavily on density gradient centrifugation. After chemical and physical characteristization, the ability of purified bacterial components to participate in the in vitro models of fetal bone resorption and macrophage activation and release of hydrolytic enzymes will be examined. The knowledge afforded in understanding the mechanisms by which bacterial cell substances can interact and activate host cell inflammatory responses should provide the much needed information to solve similar problems in inflammatory diseases similar to periodontal disease.